Light irradiation device and image forming device

Abstract

This light irradiation device is provided with: an LED substrate, on which a plurality of LED chips that emit ultraviolet light are arrayed in a first direction; and a cover capable of transmitting the ultraviolet light emitted from the LED chips. When a plane, on which an intersection point that the light emitted from the LED chips positioned at both ends in the first direction reach is positioned, said plane being parallel to an LED substrate surface, is specified as a reference plane Z1, the distance between the LED substrate surface and the reference plane Z1 is represented by D (mm), and the distance between the LED substrate surface and a cover outer surface is represented by W (mm), W satisfies formula W<D.

The invention claimed is: 
     
       1. A light irradiation device comprising:
 an LED substrate on which a plurality of LED chips that emit ultraviolet rays are arrayed in a first direction; and 
 a cover capable of transmitting the ultraviolet rays from the LED chips, 
 wherein a following expression (1) is satisfied:
     W<D   (1)
 
 
 where a reference plane Z 1  is a plane on which an intersection point where light from each of the LED chips located at both ends in the first direction reaches is located, the plane being parallel to an LED substrate surface, 
 D is a distance between the LED substrate surface and the reference plane Z 1 , 
 W is a distance between the LED substrate surface and a cover outside surface, 
 and 
 a unit of D and W is expressed in millimeter, and 
 wherein the LED chips are arranged in the first direction and a second direction orthogonal to the first direction on the LED substrate, and the distance between both ends of the plurality of LED chips arrayed in the first direction is shorter than a distance between both ends of the plurality of LED chips arrayed in the second direction. 
 
     
     
       2. The light irradiation device according to  claim 1 , wherein assuming that a reference plane Z 2  is a plane on which an intersection point where light from each of the adjacent LED chips reaches is located, the plane being parallel to the LED substrate surface, and that d (mm) is a distance between the LED substrate surface and the reference plane Z 2 , W satisfies the following expression (2):
     d<W   (2).
 
 
     
     
       3. The light irradiation device according to  claim 1 , wherein a plurality of lenses corresponding to the LEDs are arranged in front of the LED chips, and
 assuming that 2 L is a distance between the LEDs located at both ends in the first direction, and that θ is a divergence angle of the light emitted from each lens, the D is a value obtained by the following equation (3):
     D=L /tan θ  (3).
 
 
 
     
     
       4. The light irradiation device according to  claim 1 , wherein a difference (D−W) between the D and the W is greater than or equal to 3 mm. 
     
     
       5. An image forming device comprising:
 an ejection device that ejects UV ink curable by ultraviolet rays; 
 the light irradiation device according to  claim 1 ; and 
 a workpiece placement unit located on an ultraviolet ray emitting surface side of the light irradiation device, 
 wherein assuming that Y (mm) is a distance between the LED substrate surface and a mounting surface of the workpiece placement unit, Y satisfies the following expression (4):
     W<Y< 2 D   (4).
 
 
 
     
     
       6. The image forming device according to  claim 5 , wherein the light irradiation device is disposed such that a workpiece conveyance direction is matched with the first direction. 
     
     
       7. A light irradiation device comprising:
 an LED substrate on which a plurality of LED chips that emit ultraviolet rays are arrayed in a first direction; and 
 a cover capable of transmitting the ultraviolet rays from the LED chips, wherein 
 the number of LED chips arranged in the first direction is greater than or equal to three, 
 wherein a following expression (1) is satisfied:
     W<D   (1)
 
 
 where a reference plane Z 1  is a plane on which an intersection point where light from each of the LED chips located at both ends in the first direction reaches is located as a point, the plane being parallel to an LED substrate surface, 
 D is a distance between the LED substrate surface and the reference plane Z 1 , 
 W is a distance between the LED substrate surface and a cover outside surface, 
 and 
 a unit of D and W is expressed in millimeter, 
 the LED chips are arranged in the first direction and a second direction orthogonal to the first direction on the LED substrate, and the distance between both ends of the plurality of LED chips arrayed in the first direction is shorter than a distance between both ends of the plurality of LED chips arrayed in the second direction.